Multi-wall tie apparatus and method

ABSTRACT

A cavity wall which is usually made with a hollow concrete block as the inner wythe and brick as the outer wythe is disclosed. A special purpose insertion tool is fitted to a standard hammer tool. A center pin is provided in the insertion tool made with an indent to match the pointed end of the tie. The pin is then pressed into the SDS fitting which is the connection into the drill. The tie end is supported by a short sleeve which, when it contacts the face of the wall, retracts against a spring until the tie driving is completed. A modified embodiment of the adapter recognizes that the tie when activated by the hammer invariably rotates clockwise. Accordingly, if the spring is wound clockwise, the bottom tail end will dig into its seat. On the other hand, if it is wound counterclockwise, it rotates in a &#34;tail skid&#34; relationship to the seat.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a division application of Ser. No.08/721,827, filed Sep. 27, 1996 now U.S. Pat. No. 5,687,801, by the sameinventors herein entitled "Multi-Wall Tie Apparatus and Method" andallowed Mar. 20, 1997, which in turn is a continuation-in-part ofapplication Ser. No. 08/204,465, filed Feb. 28, 1994 by the sameinventors herein and entitled "Multi-Wall Tie Apparatus and Method",abandoned.

FIELD OF THE INVENTION

The present invention is directed to the subject matter of reinforcingmultiple walls usually in a building structure in which a tie isemployed to secure two adjacent walls which are parting or otherwiseneed a tieing arrangement.

BACKGROUND OF THE INVENTION

Oftentimes structures with multiple wythes brick, stone, concrete block,or even timbers are separated partly due to wind loads. The wind loadscan be applied in suction or compression. Finally, extra structureloading may be applied in the form of earthquakes, earth shifts, mudslides, and others.

Various techniques have been developed, primarily in the United Kingdom,for a method of inserting and chemically bonding stainless steel helicalties into wood and masonry to enable the repair stabilization ofmultiple wythe walls normally having cavities between the wythes.Cavities between the adjacent wythes can be very small. Sometimes evenzero in a solid wall, which nonetheless requires reinforcing.

In a proper cavity wall, the cavity will usually be one inch or more.Sometimes in the United Kingdom such cavities will be as wide as fiveinches, but normally in the two to four inch range. In the United Statesthe gap is commonly approximately one inch. One such technique ismarketed under the trademark RetroTie. Normally the tie is inserted fromthe outside wall, and the tie is driven into the inner wall where thetie itself cuts a thread in the substrate due to its rotation whilebeing hammered into the wall. With harder materials such as brick andconcrete, a pilot hole is normally drilled from the outside prior toinsertion. The drills used for the pilot holes are normally 4.5 mmdiameter drills irrespective of whether the tie is 6 or 8 mm indiameter. With certain softer materials such as soft wood, lightweightconcrete, and such more unusual materials such as clay, no pilot hole isneeded for that thickness.

The tie may be loaded into the insertion tool and a certain length leftprojecting for concluding the insertion. This length is determined bythe needs of the job. Generally softer material requires deeperpenetration. When the tie is inserted the amount of tie protruding isdriven fully into the inner wythe, that is, the end of the support tooltouches the inner wythe. After driving the tie to the required depth inthe inner wythe, the outer end is lying in a clearance hole, which isten millimeter for a six millimeter tie, or twelve millimeter for aneight millimeter tie. A plastic sleeve is pushed over the tie andpositioned adjacent to the cavity and thereafter bonding takes place byinserting in the outer wythe a bonding agent such as a polyester orepoxy resin. Exemplary of the foregoing are European Patents 0150906 and0171250BT.

An alternative for this technique employs reinforcement bars or threadedbars which are chemically bonded into both the inner and the outerwythes. Also, ties are inserted which may use expansion anchoringtechniques or anchoring techniques to fix both ends or with expansion atone end and a chemical at the other. Either one or both wythes have thechemical bonding applied.

The anchoring system as described is comparatively expensive, oftentimestoo stiff to permit differential movement between the wythes whichoccurs during the natural expansion of inner and outer wythe due totemperature and moisture variations. On the other hand, ties soldpursuant to the trademark Helifix described hereinafter have both axialload carrying characteristics and offer lateral flexibility. Moreover,they have a built-in ability to shed water that might attempt to migratefrom the outer wythe to the inner wythe.

SUMMARY OF THE PRIOR ART

The patent literature relating to the prior art is found primarily inClass 144, subclass 353, exemplary of which is Canadian Patent No.457,923 and U.S. Pat. No. 3,144,892. Additional prior patents are GermanPatent No. 935,023, Netherlands Patent No. 8,903,120, W.O. 87/01,153,British Patent No. 2,237,319, British Patent No. 12,178,099, BritishPatent No. 2,250,311, British Patent No. 2,141,773, British Patent No.2,223,556, and German Patent No. 3,716,808.

Of the above the Canadian patent is pertinent in that it shows joiningtwo pieces of timber in a splice. The same is done by a dowel havingthreads which form an angle of 45° or more to a vertical plane passingthrough the dowel. The Canadian patent fails to teach anything withregard to securing brick to brick. Indeed, it should be noted that eachof the five independent claims represent a "wooden structural unit" or"pre-fabricated wooden construction" to the exclusion of any other typeof material. Thus, it is inapplicable to the use of a tie which is inessence a twisted flatened the use of a tie which is in essence atwisted flatened section with a central core and driven through twoparallel wythes either brick to brick, mortar to brick, brick to woodenframe, and the like. The U.S. Pat. No. 3,144,892 to Webster just likethe Canadian patent, each of the independent claims, here six in number,refer to a method of fabricating panels each panel being referenced as"wood panel components". Thus Webster, like the Canadian patent, failsto even address securing adjacent wythes of brick or other buildingcomponents in an existing building to each other in reinforcingengagement.

SUMMARY OF THE INVENTION

The invention finds significant utility in a cavity wall which isusually made with a hollow concrete block as the inner wythe and brickas the outer wythe. The cavity is usually one-half to one inches and upto two inches between the two. The gap may vary from two inches to fiveinches or more. The system utilizes a spiral tie which is approximately7-8 inches or longer. Sometimes the length can be as long as 11 inches,but may be longer or shorter depending upon the materials and the jobsite. With a 5 to 6 millimeter pilot hole drilled to the accuracynormally which can be achieved in a brick, the end of the tie will enterthe pilot hole quite easily and cleanly. In the two step tie, thediameter is 6 millimeters and 8 millimeters, respectively, but mayincrease or decrease depending upon the application and materials. Aspecial purpose insertion tool is fitted to a standard hammer tool. Acenter pin is provided in the insertion tool made with an indent tomatch the pointed end of the tie. The pin is then pressed into the SDSfitting which is the connection into the drill. The tie end is supportedby a short sleeve which, when it contacts the face of the wall, retractsagainst a spring until the tie driving is completed. Usually the pinhammers out a short annular recess below the outer surface of the wall.A modified embodiment of the adapter recognizes that the drill whichactivates the hammer invariably rotates clockwise. Accordingly, if thespring is wound clockwise, the bottom tail end will dig into its seat.On the other hand, if it is wound counterclockwise, it rotates in a"tail skid" relationship to the seat. During the course of insertion,the pull-out resistance of the tie can be checked by using a pull unit.Normally the pull-out load requires determination one wythe at a time.This is achieved by drilling a clearance hole in the first wythe tomeasure the load achieved from the second wythe by inserting the tieinto one wythe only.

In view of the foregoing, it is a principal object of the presentinvention to provide a method and apparatus for tieing wythes togetherwhich is highly economical both from a cost standpoint of manufacture,and from the standpoint of the labor involved in achieving the fix, andalso importantly by the elimination of the cost and hazards of a bondingchemical.

Yet another object of the present invention is to provide a multiplewythe apparatus tie and method in which the speed of insertion is high,namely one minute per tie, thereby providing a wall with sixty ties tobe secured in approximately one hour.

An additional object of the present invention results from leaving ahole in the wall face which is small, thus minimizing the marking of thewall face, and permitting a small amount of material to be inserted overthe tie to mask and seal and water proof.

An additional advantage of the subject apparatus and method is toprovide excellent holding power along with significant lateralflexibility to accommodate expansion, contraction, wind loads, and evenearth tremors.

Finally, but not conclusively, another advantage of the apparatus andmethod permits application on a year round basis with an instantaneousfix, and eliminating the need for a chemical bond which requires certainclimatic conditions in order to cure for a full fix and has health andsafety implications in its use.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects and advantages of the present invention will becomeapparent as the following description of an illustrative embodimentproceeds, taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates diagrammatically a double wythe wall in which one ofthe ties penetrates the mortar between bricks, and the other tiepenetrates the brick body itself;

FIG. 2 is a transverse sectional view taken along section line 2--2 ofFIG. 1 showing the relationship of the tie and the two adjacent walls;

FIG. 3 is taken along section line 3--3 of FIG. 1;

FIG. 4 is a front elevation of the exemplary tie utilized in the method;

FIG. 5 is an end view of the tie shown in FIG. 4 and in slightlyenlarged scale;

FIG. 6 shows an alternative embodiment tie the pilot end of which is adiameter smaller than the main body portion;

FIG. 7 is an illustrative view of a workman and a hammer drill insertinga tie illustrative of the present invention into a wall having twowythes where the first penetration is mortar and the second penetrationis into a solid such as brick or concrete block;

FIG. 8 is a partially diagrammatic view of the hammer drill attachmentwhich produces a unique action in the hammering process enhancing themethod of inserting the ties;

FIG. 9 is an exploded view of the adapter shown in FIG. 8;

FIG. 10 is an enlarged view of the area shown in phantom lines by circle10 in FIG. 8 and illustrating the rotational and non-rotational motionof the critical parts while being hammered;

FIGS. 11, 12, AND 13 are sequential views of the testing technique whichis selectively utilized to determine the holding power of the tie in theinner wythe in which FIG. 11 illustrates the boring of a large hole inthe first wythe and a pilot hole in the second wythe; FIG. 12illustrates the hammering action through a sleeve in which the fix issecured into the second wythe; and FIG. 13 shows the application of atensionometer secured to the tie to determine the tension required todislodge the tie from the inner wythe;

FIG. 14 is a view of tho modified adapter approximately the same sizeand section as that shown in FIG. 9 of the original adapter;

FIG. 15 is a view similar to FIG. 10, but also illustrating the modifiedadapter; and

FIG. 16 is an exploded perspective view of the modified adapter.

DESCRIPTION OF PREFERRED EMBODIMENT

Background

Prior to describing an example of the use of the present method andapparatus it should be remembered that in tieing two wythes in a walltogether, it can be done from the outside to the inside, and from theinside to the outside. This is particularly important with historicbuildings during total rehabilitation when the interior is gutted, andnew interior is installed with a new interior wall or wythe, and then itis desired to tie the same to the original outer wall or wythe. The tiematerials used are preferably stainless steel, Austenitic grades 304 or316. The ties also can be made of other materials, and including tubularrather than solid, although best results have occurred with solidstainless steel materials. The drilling machine 20 employed such asshown in FIG. 7, is electric, air driven, or hydraulically operated.They employ SDS, SDS+, and SDS Max chucks. All of these are Boschpatented designs. The drilling machine can employ a roto stop feature.Also chiseling machines may be employed without rotary motion so long asthe tie is permitted to rotate. The diameter maintained is usually 8millimeters. Other sizes are possible for the ties such as 4.5 and 6.0millimeters. Ten to 12 millimeters are both possible for certain highload applications. Also in some instances the number of wythes can bemore than two. The only limitation on the number of wythes that can besecured is the strength of the tie and the machine power. Moreover, thewall may be brick/brick, brick/block, block/brick, block/block,brick/wood, block/wood, brick/concrete, and even terracotta typematerials.

The Method

With the foregoing background in mind, the method will be reviewed as itaddresses a wall 1 such as shown in exemplified form in FIG. 1. There itwill be seen that the wall 1 includes an outer wythe 2, an inner wythe4, and a plurality of structural members 6 joined by mortar 5. A tie 10is driven through the outer hole 30 and into the inner hole 31 as willbe described in greater detail hereinafter. In all applications mostdesirably the tie proceeds brick to brick, or at least mortar to brick.Preferably the inner wythe tie engaging member is solid. Further, theouter and inner holes are desirably at least 1 millimeter less indiameter than the tie 10.

Referencing now FIG. 2, there it will be seen that the tie 10 is passingthrough outer hole 30 in the mortar 5 into inner hole 31 in the brick 4where the inserted tie 10 can be subsequently used to assess thetension. In FIG. 3, the outer hole 30 is employed with a same diameterinner hole 31 in the inner wythe 4 for total penetration by the tie 10.Desirably the outer hole 30 and inner hole 31 are the same diameterwhether brick to brick or mortar to brick.

FIG. 4 illustrates the typical tie 10 having a beveled or chiseled end11, and a plurality of helical wound flutes 12 which surround a core 15.As stated earlier, Austenitic steel of grades 304 or 316 are desirablyutilized in forming the ties 10.

A two-step tie is shown in FIG. 6. There it will be seen that the smallend 16 of the two step tie 15 is at the left-hand side and the large end18 at the right-hand side with a step 19 between the two. The variousdesirable dimensions will be discussed hereinafter.

FIG. 7 illustrates the utilization of a hammer drill 20 held by anoperator 21 in which he holds the adapter 22 in his right hand and thehammer drill 20 in his left hand. It will also be appreciated that thedrill can be held in the right hand which is often a normal usage. Thetie 10 is being passed through the outer wythe 2 and mortar 5 into theinner wythe 4.

After the wall is tied together, the tie 10 thus helically grasps theinterior wythe 4 as well as the exterior wythe 2, and a dry fix ortieing relationship is developed. The outer portion of the tie 10 willbe buried slightly underneath the outer wythe 2, and the hole left isfilled with an adhesive or sealing agent, sometimes mixed with dust fromwythe 2 to disguise and seal the hole.

The Adapter

It is necessary to appreciate that the power source is a hammer drillingmachine 20 fitted with an SDS chuck. The hammer action against the tie10 causes the tie to rotate as the helical roll penetrates the masonry.It is important that the tie be free to rotate in the nose of theadapter to avoid creating any stress in the masonry other than thatimparted by the hammering action of the tie. The tie, in turn, willalways follow a "natural" path which is the usual path of leastresistance. The stroke of the hammer action is around 10 millimeter.

For the present application use is made only of the hammer action. Somedrilling machines have a feature called "roto stop" which can beselected and cuts out the rotary drive to the chuck, leaving only thehammer action. Electric or pneumatic chisel machines normally have thehammer action only.

As most drilling machines commonly found on site do not have the rotostop feature, the present adapter 22 has to be such as to permit its useboth with a machine with rotary hammer action as well as one with hammeronly.

The spring 45 and spring loaded sleeve 48 have any rotational movementimparted by friction only. When the nose of the spring loaded sleeve 48hits the wall, the stainless steel flutes 12 in the tie 10 arecontinually driven into the wall, the spring 45 is compressed until theend of the sleeve 48 is flush with the front end screw 49. The drawingshows the tool set up so that the driving pin 46 will project beyond theend of the sleeve 48 and will drive the tie 10 under the surface of theouter wythe 2 face. The drive pin 46 may be set to finish or set the tie10 set flush. The flush setting is usually only used when the tie 10 isbeing driven into wood. The outer handle 40 is fitted with a metalbearing 50 at each end. This is held by the operator 21 usually and allthe action goes on freely inside it, both rotational and to-and-fro. Thetie 10 is driven by the cupped end 51 of the drive pin 46.

The Modified Adapter

The modified adapter 70 is best illustrated in FIGS. 14-16. Here itshould be remembered that the drill which activates the hammer and thehammer SDS chuck will rotate clockwise. Thus, as the rotation driven bythe tie 10 creeps in a clockwise direction, the coil spring 78compresses and drives the spring loaded spring ends rotatably clockwiseor right-handed. With the modified adapter 70, it will be seen that itutilizes an outer body 71 which runs substantially the entire length ofthe modified adapter 70. A drive pin 72 is positioned centrally of thebody 71. The drive pin 72 engages a split bearing 73 which is seatedwithin the outer body 71. A spring seating washer 74 is held against thesplit bearing 73 by the spring 78. A front sleeve 75 is securedinteriorly of the forward portion of the outer body 71. A tapered SDSadapter 76 is seated upon the driven end of the drive pin 72. The splitbearing 73 is sandwiched in place against the spring seating washer 74by means of the snap ring 77. The activity is applied by means of thecoil spring 78 which is left-hand or counterclockwise wound rather thanright-hand or clockwise wound. This is done to cause the remote end ofthe spring 78 to engage the spring seating washer 74 in a "tail skid"relationship. This action is similarly involved with the opposite end ofthe spring 78. The front sleeve 75 is secured in place interiorly of theouter body 71 by means of set screw 79. The outer body 71 is covered atits portion closest to the SDS adapter 76 by a plastic cover sleeve 80which is in close fitting engagement to the outer body 71, and extendsthroughout about half of the length of the outer barrel 71. A centrallydisposed collar 81 is located at the remote end of the plastic coversleeve 80. To be noted specifically is that the spring 78 seats at thesplit bearing 73 end in the spring seating washer 74 and is securedtherein by means of the collar 83. At the opposite end, an annular space84 terminating in a shoulder 85 is defined between the inner portion ofthe front sleeve 75 and the inner portion of the outer body 71.

The 2 Diameter Tie

Normally a suitable pilot drill is driven through consecutive wythes andthe helical tie 10 is driven home. Where the materials of the differentwythes are similar or, at least, are of similar strength, this worksfine.

Where the outer wythe 2 is harder/stronger than the inner wythe 4materials then, on occasions, it may be necessary to drill a first holeright through which is correct for the softer/weaker materials and thenuse a slightly larger pilot in the harder material only.

The problem comes where the outer material is soft, requiring thesmaller hole and the inner material is hard requiring a larger hole. Theexample which demands this new technique occurs where there is arequirement to fix through the mortar joint in the outer wythe and fixinto reinforced concrete or brick. With the two diameter tie 15 of FIG.6 one can use a single drill through the mortar and into the concrete orbrick. The small end 16 is then driven into the hard material and thelarge end 18 will still get a good grip in the softer, outer wythemortar. The two step tie 15 proves useful, not just in the mortar bed toconcrete application above, but in any application where one wants tofix soft/weak to hard/strong. The division between the small end 16 andlarge end 18 forms a step 19 in the two step tie 15. The small end 16 isnormally but not necessarily the shorter end, about one third the lengthof the two step tie 15.

Load Test Unit

The load test unit or tensionometer 25 uses a small hydraulic cell whichhas pressure applied to it by a jacking screw or actuator 29. Thepressure is measured by the gauge 28 which is calibrated to give adirect reading of force applied when engaged to a tie 10 by the loadtest key 26.

The load test key 26 fits over the end of the tie imparting no torsionalload and only an end load. The cross piece of the key fits into the endof the central shaft and an axial load is applied by turning the jackingnut or actuator 29.

With the illustrated system it is not possible to test the tie in itsfinal fixed state. The strength of the inner wythe is determined bymaking a clearance hole in the outer and driving the tie into the innerwythe or by using a core drill to create a clearance hole around the endof the tie in the outer wythe after insertion. The load test unit 25 isapplied and the strength is determined. This is repeated at severallocations around the building and usually the weakest load obtained isused for the design of the fixing pattern.

Similarly the outer wythe 2 is tested by driving a tie 10 through theouter wythe 2 only--not into the inner 4 --and applying the load testunit 25 to measure the strength.

Although particular embodiments of the invention have been shown anddescribed in full here, there is no intention to thereby limit theinvention to the details of such embodiments. On the contrary, theintention is to cover all modifications, alternatives, embodiments,usages and equivalents as fall within the spirit and scope of thepresent invention, specification and appended claims.

What is claimed is:
 1. A two-step tie for use in securing multiple wallstogether comprising, in combination,a helical body portion havinghelical portions; said helical body portion having a central core inwhich the helical portions are joined at a mid-point; and one helicalportion having a diameter smaller than the other, both helical sectionshaving a pitch in the same direction, and one end of the tie beingcharacterized by a cutting configuration, the two helical portions whichare joined at the mid-point have the same pitch in opposite directionsaway from the mid-point.
 2. The two-step tie of claim 1, in which:thesmaller diameter portion of the two step tie having a length less thanone half the total length of the tie.